1. Field of the Invention
The present invention relates to a magnetic switching device and a magnetic memory using the same.
2. Description of the Related Art
Magnetic switching devices including a magnetic substance, for performing conversion between electric energy and magnetic energy, are used for various magnetic devices such as a reproducing head of a magnetic recording apparatus, sensors (e.g., a force sensor, an acceleration sensor, etc.), and magnetic solid memories (e.g., a magnetic random access memory, etc.). However, such a magnetic switching device has a problem of a low energy conversion efficiency as described below, and hence, there is a demand for a magnetic switching device with a higher energy conversion efficiency (i.e., with reduced power consumption).
As a method for controlling a magnetic switching device, for example, the magnetized state of a magnetic substance included in a magnetic switching device is changed, and as a more specific example, the magnetization direction of the magnetic substance is reversed. The magnetized state of a magnetic substance generally is known to be determined by the sum of exchange energy, crystal magnetic anisotropic energy, magnetostatic energy, and Zeeman energy generated by an external magnetic field. Among them, the physical amounts that can be controlled so as to change the magnetized state are magnetostatic energy and Zeeman energy. Therefore, in the case of controlling the magnetized state of a magnetic substance with electric energy, an external magnetic field generated when a current flows has been used conventionally. However, for example, the energy conversion efficiency for generation of a magnetic field with a line current is about 1%. Furthermore, in the case of the line current, the intensity of a generated magnetic field is inversely proportional to a distance. In most cases, it is necessary to place an insulator between a lead through which a line current is allowed to flow and a magnetic substance in a magnetic switching device. Therefore, it is considered that the energy conversion efficiency is decreased to a level less than 1%. Such a low energy conversion efficiency is considered to be a factor that prevents a magnetic switching device and a magnetic device using the magnetic switching device from further spreading.